72 BROOKS— HEREDITY AND VARIATION; [April 20, 



as facts, as they seem to me to be only imperfect ideas of facts, 

 mental states which have arisen through a partial and uncritical view 

 of our experience, to the neglect of that which has not interested us 

 nor seemed to concern us. 



If you agree with me that resemblance to ancestors does not 

 exist in nature separated from individuality or difference from an- 

 cestors, that inheritance is not a fact but an imperfect idea of facts, 

 admitting of improvement by comparison with nature, and in no 

 other way, — if you agree to this, what becomes of the notion of a 

 substance of inheritance? There is, no doubt, a material equivalent 

 for every mental concept, and the material equivalent of heredity 

 may be in the brain of the speculative philosopher, for I cannot find 

 it in living beings nor in germ cells nor in chromatin. 



I hope you will not accuse me of opposing the scientific study 

 of inheritance and variation, for nothing is farther from my inten- 

 tion. The resemblances and differences between ancestors and de- 

 scendants are as worthy of study as arithmetic, which has been of 

 inestimable value to mankind although there is in nature no quantity 

 without quality. 



We cannot make progress in natural knowledge without special- 

 izing ; picking out what interests us and ignoring what does not seem 

 to concern us ; but specialization is not an unmixed benefit, and if 

 it blinds our eyes to the real world that lies before them it may 

 prove to be an unmitigated evil ; leading the modern scientific man 

 into the forlorn agnosticism of the ancient philosophers who held 

 that we can never know anything because no real thing exists ab- 

 stractly. Things do not cease to be because we fail to note them, 

 and when we fix our attention upon some partial and imperfect con- 

 ception of nature to the neglect of that which does not interest us, 

 we may forget the reality of that which we have failed to consider, 

 and we may thus be led to opinions which seem to be the logical con- 

 clusions of sound reasoning when they are but new illustrations of 

 the threadbare fallacy of the undistributed middle — the fallacy which 

 comes from mistaking a part for a whole. 



The paradoxes into which the biologists fall in their efforts to 

 locate the substance of inheritance remind me of the perplexity of 

 the school boy, who, having tried to add together six horses and 



